Comparison of Near-Surface Wind Speed Estimation Techniques Using Different Damage Indicators from a Damage Survey of Naplate, IL EF-3 Tornado
Publication: Natural Hazards Review
Volume 23, Issue 1
Abstract
Estimation of tornado wind speed can be extremely difficult, especially near the ground where tornado damage occurs. Because of limitations of in situ measurements, ground-based damage surveys continue to be the most commonly used method to estimate the near-surface wind speed. This study discusses a comprehensive damage assessment of Naplate, Illinois (IL) tornado that occurred in February 2017. The damage survey included the following damage indicators: residential buildings, trees, and traffic signs. Additional data from social media images were collected and used to supplement the damage assessment. This comprehensive data set of damage indicators was used to estimate the characteristics of the Naplate, IL tornado. Multiple wind-speed estimation methods, each suited to a subset of the damage indicators, were applied to estimate the near-surface wind field of the tornado. The results from all independent methods were compared to create a cross-validated estimation of the surface tornado wind field. The similarity between estimates derived from different damage indicators and methods increases confidence in the wind speed estimation and validates the independent application of any of the methods presented, with each being appropriate for given circumstances and data availability.
Get full access to this article
View all available purchase options and get full access to this article.
Data Availability Statement
All data, models, and code generated or used during the study appear in the published article.
Acknowledgments
The damage survey of Naplate, IL tornado was funded by the NOAA VORTEX-SE program (Award Nos. NA150AR4590228 and NA16OAR4590219). The authors gratefully acknowledge the financial support of VORTEX-SE. The authors thank Antonio Zaldivar, Guangzhao Chen, Alexander Zickar, Rishabh Moorjani, Amanda R. Lombardo, and Jennifer Vetrone for contributing to the damage survey. The authors also are grateful to ProVisional Shot (now known as Cantu Media Group, LLC) for the use of their social media images in this paper. Dr. Godfrey and Dr. Peterson for providing the Joplin, MO tornado tree data. Nafiz Rahman for collecting social media images of the Naplate, IL tornado. Jiachen Xin for helping with the data collection and analysis of traffic signs. Special thanks are given to the Village of Naplate and the residents for providing information on structures and being gracious hosts, and NWS Chicago for sharing their findings and rationale for their damage survey of Naplate.
References
AISC. 2017. Steel construction manual. Chicago: AISC.
Amini, M. O., and J. W. van de Lindt. 2014. “Quantitative insight into rational tornado design wind speeds for residential wood-frame structures using fragility approach.” J. Struct. Eng. 140 (7): 04014033. https://doi.org/10.1061/(ASCE)ST.1943-541X.0000914.
ASCE. 2016. Minimum design loads for buildings and other structures. Reston, VA: ASCE.
Atkins, N. T., K. M. Butler, K. R. Flynn, and R. M. Wakimoto. 2014. “An integrated damage, visual, and radar analysis of the 2013 Moore, Oklahoma, EF5 tornado.” Bull. Am. Meteorol. Soc. 95 (10): 1549–1561. https://doi.org/10.1175/BAMS-D-14-00033.1.
Bech, J., M. Gayà, M. Aran, F. Figuerola, J. Amaro, and J. Arús. 2009. “Tornado damage analysis of a forest area using site survey observations, radar data and a simple analytical vortex model.” Atmos. Res. 93 (1–3): 118–130. https://doi.org/10.1016/j.atmosres.2008.10.016.
Beck, V., and N. Dotzek. 2010. “Reconstruction of near-surface tornado wind fields from forest damage.” J. Appl. Meteorol. Climatol. 49 (7): 1517–1537. https://doi.org/10.1175/2010JAMC2254.1.
Blanchard, D. O. 2013. “A comparison of wind speed and forest damage associated with tornadoes in northern Arizona.” Weather Forecasting 28 (2): 408–417. https://doi.org/10.1175/WAF-D-12-00046.1.
Bluestein, H. B. 2007. “Mobile Doppler radar observations of tornadoes.” Accessed March 11, 2020. http://www.essl.org/ECSS/2007/abs/05-Radars/bluestein-1177432754.pdf.
Bluestein, H. B., K. J. Thiem, J. C. Snyder, and J. B. Houser. 2019. “Tornadogenesis and early tornado evolution in the El Reno, Oklahoma, supercell on 31 May 2013.” Mon. Weather Rev. 147 (6): 2045–2066. https://doi.org/10.1175/MWR-D-18-0338.1.
Boughton, G. N., D. J. Henderston, J. D. Ginger, J. D. Holmes, G. R. Walker, C. J. Leitch, L. R. Somerville, U. Frye, N. C. Jayasinghe, and P. Y. Kim. 2012. Tropical Cyclone Yasi: Structural damage to buildings. Towsnville, QLD, Australia: Cyclone Testing Station, James Cook Univ.
Burgess, D., et al. 2014. “20 May 2013 Moore, Oklahoma, tornado: Damage survey and analysis.” Weather Forecasting 29 (5): 1229–1237. https://doi.org/10.1175/WAF-D-14-00039.1.
Cannon, J. B., M. E. Barrett, and C. J. Peterson. 2015. “The effect of species, size, failure mode, and fire-scarring on tree stability.” For. Ecol. Manage. 356 (Nov): 196–203. https://doi.org/10.1016/j.foreco.2015.07.014.
Changnon, S. A. 2009. “Tornado losses in the United States.” Nat. Hazard. Rev. 10 (4): 145–150. https://doi.org/10.1061/(ASCE)1527-6988(2009)10:4(145).
Chen, G., and F. T. Lombardo. 2019. “An analytical pattern-based method for estimation of a near-surface tornadic wind field.” J. Wind Eng. Ind. Aerodyn. 194 (Nov): 103999. https://doi.org/10.1016/j.jweia.2019.103999.
Cook, N. J. 1990. The designer’s guide to wind loading of building structures. Part 2: Static structures. London: Building Research Establishment.
Coulbourne, W. L., and J. Miller. 2012. “Performance of school buildings in the Joplin, MO, tornado.” In Proc., Structures Congress 2012, 989–998. Reston, VA: ASCE.
Crawford, P. S., A. Graettinger, L. Powell, S. Awondo, E. Back, and S. Spector. 2017. “Five years after the April 27, 2011, Tuscaloosa tornado: A study in community resilience.” In Proc., AEI 2017, 758–769. Reston, VA: ASCE.
Cucchi, V., C. Meredieu, A. Stokes, S. Berthier, D. Bert, M. Najar, A. Denis, and R. Lastennet. 2004. “Root anchorage of inner and edge trees in stands of Maritime pine (Pinus pinaster Ait.) growing in different podzolic soil conditions.” Trees 18 (4): 460–466. https://doi.org/10.1007/s00468-004-0330-2.
Cutter, S. L., and C. Emrich. 2005. “Are natural hazards and disaster losses in the US increasing?” EOS Trans. AGU 86 (41): 381–389. https://doi.org/10.1029/2005EO410001.
Doswell, C. A., III. 2003. A guide to F-scale damage assessment. Silver Spring, MD: National Oceanic and Atmospheric Administration.
Doswell, C. A., III, H. E. Brooks, and N. Dotzek. 2009. “On the implementation of the enhanced Fujita scale in the USA.” Atmos. Res. 93 (1–3): 554–563. https://doi.org/10.1016/j.atmosres.2008.11.003.
Doviak, R. J., and D. S. Zrnić. 2006. “Observations of winds, storms, and related phenomena.” Chapter 9: Doppler radar and weather observations, 280–385. San Diego: Academic Press. https://doi.org/10.1016/B978-0-12-221422-6.50014-0.
Edwards, R., J. G. LaDue, J. T. Ferree, K. Scharfenberg, C. Maier, and W. L. Coulbourne. 2013. “Tornado intensity estimation: Past, present, and future.” Bull. Am. Meteorol. Soc. 94 (5): 641–653. https://doi.org/10.1175/BAMS-D-11-00006.1.
Ellingwood, B. R., D. V. Rosowsky, Y. Li, and J. H. Kim. 2004. “Fragility assessment of light-frame wood construction subjected to wind and earthquake hazards.” J. Struct. Eng. 130 (12): 1921–1930. https://doi.org/10.1061/(ASCE)0733-9445(2004)130:12(1921).
Emmer, A. 2018. “Geographies and scientometrics of research on natural hazards.” Geosciences 8 (10): 382. https://doi.org/10.3390/geosciences8100382.
ESDU (Engineering Sciences Data Unit). 1989. Boundary walls, fences and hoardings: Mean and peak wind loads and overturning moments, data item 89050. London: ESDU.
Fujita, T. T. 1970. “The Lubbock tornadoes: A study of suction spots.” Weatherwise 23 (4): 161–173. https://doi.org/10.1080/00431672.1970.9932888.
Fujita, T. T. 1989. “The Teton-Yellowstone tornado of 21 July 1987.” Mon. Weather Rev. 117 (9): 1913–1940. https://doi.org/10.1175/1520-0493(1989)117%3C1913:TTYTOJ%3E2.0.CO;2.
Gillmeier, S., M. Sterling, H. Hemida, and C. J. Baker. 2018. “A reflection on analytical tornado-like vortex flow field models.” J. Wind Eng. Ind. Aerodyn. 174 (Mar): 10–27. https://doi.org/10.1016/j.jweia.2017.12.017.
Godfrey, C. M., C. D. Karstens, D. Rhee, C. J. Peterson, and F. T. Lombardo. 2020. “A comparison of three wind speed estimation techniques based on tornado-induced treefall patterns.” Accessed March 11, 2020. https://ams.confex.com/ams/2020Annual/meetingapp.cgi/Paper/367584.
Godfrey, C. M., and C. J. Peterson. 2017. “Estimating enhanced Fujita scale levels based on forest damage severity.” Weather Forecasting 32 (1): 243–252. https://doi.org/10.1175/WAF-D-16-0104.1.
Guyer, J. L., and M. L. Moritz. 2003. “On issues of tornado damage assessment and F-scale assignment in agricultural areas.” In Proc., 83rd AMS Annual Meeting Symp. on F-scale and Severe-weather Damage Assessment. Boston: American Meteorological Society.
Hall, F., and R. D. Brewer. 1959. “A sequence of tornado damage patterns.” Mon. Weather Rev. 87 (6): 207–216. https://doi.org/10.1175/1520-0493(1959)087%3C0207:ASOTDP%3E2.0.CO;2.
Holland, A. P., A. J. Riordan, and E. C., Franklin. 2006. “A simple model for simulating tornado damage in forests.” J. Appl. Meteorol. Climatol. 45 (12): 1597–1611. https://doi.org/10.1175/JAM2413.1.
Holland, G. J. 1980. “An analytic model of the wind and pressure profiles in hurricanes.” Mon. Weather Rev. 108 (8): 1212–1218. https://doi.org/10.1175/1520-0493(1980)108%3C1212:AAMOTW%3E2.0.CO;2.
Holmes, J. D. 2015. Wind loading of structures. Boca Raton, FL: CRC Press.
IDOT (Illinois DOT). 2016. Standard specification for road and bridge construction. Springfield, IL: IDOT.
Karstens, C. D., W. A. Gallus Jr., B. D. Lee, and C. A. Finley. 2013. “Analysis of tornado-induced tree fall using aerial photography from the Joplin, Missouri, and Tuscaloosa–Birmingham, Alabama, tornadoes of 2011.” J. Appl. Meteorol. Climatol. 52 (5): 1049–1068. https://doi.org/10.1175/JAMC-D-12-0206.1.
Karstens, C. D., T. M. Samaras, B. D. Lee, W. A. Gallus Jr., and C. A. Finley. 2010. “Near-ground pressure and wind measurements in tornadoes.” Mon. Weather Rev. 138 (7): 2570–2588. https://doi.org/10.1175/2010MWR3201.1.
Knox, J. A., et al. 2013. “Tornado debris characteristics and trajectories during the 27 April 2011 super outbreak as determined using social media data.” Bull. Am. Meteorol. Soc. 94 (9): 1371–1380. https://doi.org/10.1175/BAMS-D-12-00036.1.
Kosiba, K., and J. Wurman. 2010. “The three-dimensional axisymmetric wind field structure of the Spencer, South Dakota, 1998 tornado.” J. Atmos. Sci. 67 (9): 3074–3083. https://doi.org/10.1175/2010JAS3416.1.
Kosiba, K. A., and J. Wurman. 2013. “The three-dimensional structure and evolution of a tornado boundary layer.” Weather Forecasting 28 (6): 1552–1561. https://doi.org/10.1175/WAF-D-13-00070.1.
LaDue, J. G., et al. 2020. “Demonstrating a future application of the wind speed estimation standard to tornadoes.” Accessed March 11, 2020. https://ams.confex.com/ams/2020Annual/meetingapp.cgi/Paper/367140.
Lee, K. H., and D. V. Rosowsky. 2005. “Fragility assessment for roof sheathing failure in high wind regions.” Eng. Struct. 27 (6): 857–868. https://doi.org/10.1016/j.engstruct.2004.12.017.
Letchford, C. W. 2001. “Wind loads on rectangular signboards and hoardings.” J. Wind Eng. Ind. Aerodyn. 89 (2): 135–151. https://doi.org/10.1016/S0167-6105(00)00068-4.
Lombardo, F. T. 2018. “Engineering analysis of a full-scale high-resolution tornado wind speed record.” J. Struct. Eng. 144 (2): 04017212. https://doi.org/10.1061/(ASCE)ST.1943-541X.0001942.
Lombardo, F. T., D. B. Roueche, and D. O. Prevatt. 2015. “Comparison of two methods of near-surface wind speed estimation in the 22 May, 2011 Joplin, Missouri tornado.” J. Wind Eng. Ind. Aerodyn. 138 (Mar): 87–97. https://doi.org/10.1016/j.jweia.2014.12.007.
Löw, P. 2020. “Tropical cyclones cause highest losses.” Munich RE. Accessed February 24, 2020. https://www.munichre.com/topics-online/en/climate-change-and-natural-disasters/natural-disasters/natural-disasters-of-2019-in-figures-tropical-cyclones-cause-highest-losses.html.
Mansour, M. A., D. M. Rhee, T. Newson, C. Peterson, and F. T. Lombardo. 2021. “Estimating wind damage in forested areas due to tornadoes.” Forests 12 (1): 17. https://doi.org/10.3390/f12010017.
Masoomi, H., M. R. Ameri, and J. W. van de Lindt. 2018. “Wind performance enhancement strategies for residential wood-frame buildings.” J. Perform. Constr. Facil. 32 (3): 04018024. https://doi.org/10.1061/(ASCE)CF.1943-5509.0001172.
McDonald, J. R., and K. C. Mehta. 2006. A recommendation for an Enhanced Fujita scale (EF-Scale). Luddock, TX: Wind Science and Engineering Center, Texas Tech Univ.
Memari, M., N. Attary, H. Masoomi, H. Mahmoud, J. W. van de Lindt, S. F. Pilkington, and M. R. Ameri. 2018. “Minimal building fragility portfolio for damage assessment of communities subjected to tornadoes.” J. Struct. Eng. 144 (7): 04018072. https://doi.org/10.1061/(ASCE)ST.1943-541X.0002047.
Middleton, S. E., L. Middleton, and S. Modafferi. 2013. “Real-time crisis mapping of natural disasters using social media.” IEEE Intell. Syst. 29 (2): 9–17. https://doi.org/10.1109/MIS.2013.126.
Nevill, J. B., and F. T. Lombardo. 2020. “Structural functionality scale for light-framed wood buildings with indicators for windstorm damage.” J. Struct. Eng. 146 (4): 04020033. https://doi.org/10.1061/(ASCE)ST.1943-541X.0002551.
Nevill, J. B., and F. T. Lombardo. 2021. “Empirical tornado resilience model for light-framed wood residential buildings.” Eng. Struct. 231 (Mar): 111840. https://doi.org/10.1016/j.engstruct.2020.111840.
NOAA (National Oceanic and Atmospheric Administration). 2019. “Tornadoes—Annual 2017.” National Centers for Environmental Information. Accessed March 11, 2020. https://www.ncdc.noaa.gov/sotc/tornadoes/201713.
Peltola, H., and S. Kellomäki. 1993. “A mechanistic model for calculating windthrow and stem breakage of Scots pines at stand age.” Silva Fenn. 27 (2): 99–111. https://doi.org/10.14214/sf.a15665.
Peltola, H., S. Kellomäki, A. Hassinen, and M. Granander. 2000. “Mechanical stability of Scots pine, Norway spruce and birch: An analysis of tree-pulling experiments in Finland.” For. Ecol. Manage. 135 (1–3): 143–153. https://doi.org/10.1016/S0378-1127(00)00306-6.
Peltola, H., M. L. Nykänen, and S. Kellomäki. 1997. “Model computations on the critical combination of snow loading and windspeed for snow damage of scots pine, Norway spruce and Birch sp. at stand edge.” For. Ecol. Manage. 95 (3): 229–241. https://doi.org/10.1016/S0378-1127(97)00037-6.
Peltola, H. M. 2006. “Mechanical stability of trees under static loads.” Am. J. Bot. 93 (10): 1501–1511. https://doi.org/10.3732/ajb.93.10.1501.
Peterson, C. J. 2007. “Consistent influence of tree diameter and species on damage in nine eastern North America tornado blowdowns.” For. Ecol. Manage. 250 (1–2): 96–108. https://doi.org/10.1016/j.foreco.2007.03.013.
Peterson, C. J., and V. Claassen. 2013. “An evaluation of the stability of Quercus lobata and Populus fremontii on river levees assessed using static winching tests.” Forestry 86 (2): 201–209. https://doi.org/10.1093/forestry/cps080.
Prevatt, D. O., D. B. Roueche, J. W. van de Lindt, S. Pei, T. Dao, W. Coulbourne, A. Graettinger, R. Gupta, and D. Grau. 2012a. “Building damage observations and EF classifications from the Tuscaloosa, AL, and Joplin, MO, tornadoes.” In Proc., Structures Congress 2012. 999–1010. Reston, VA: ASCE.
Prevatt, D. O., J. W. van de Lindt, E. W. Back, A. J. Graettinger, S. Pei, W. Coulbourne, R. Gupta, D. James, and D. Agdas. 2012b. “Making the case for improved structural design: Tornado outbreaks of 2011.” Leadersh. Manage. Eng. 12 (4): 254–270. https://doi.org/10.1061/(ASCE)LM.1943-5630.0000192.
Radhika, S., Y. Tamura, and M. Matsui. 2015. “Cyclone damage detection on building structures from pre-and post-satellite images using wavelet based pattern recognition.” J. Wind Eng. Ind. Aerodyn. 136 (Jan): 23–33. https://doi.org/10.1016/j.jweia.2014.10.018.
Rankine, W. J. M. 1882. A manual of applied physics. London: Charles Griff.
Refan, M., H. Hangan, J. Wurman, and K. Kosiba. 2017. “Doppler radar-derived wind field of five tornado events with application to engineering simulations.” Eng. Struct. 148 (Oct): 509–521. https://doi.org/10.1016/j.engstruct.2017.06.068.
Rhee, D. M., and F. T. Lombardo. 2018. “Improved near-surface wind speed characterization using damage patterns.” J. Wind Eng. Ind. Aerodyn. 180 (Sep): 288–297. https://doi.org/10.1016/j.jweia.2018.07.017.
Rhee, D. M., F. T. Lombardo, and J. Kadowaki. 2021. “Semi-automated tree-fall pattern identification using image processing technique: Application to Alonsa, MB tornado.” J. Wind Eng. Ind. Aerodyn. 208 (Jan): 104399. https://doi.org/10.1016/j.jweia.2020.104399.
Rosowsky, D. V., and B. R. Ellingwood. 2002. “Performance-based engineering of wood frame housing: Fragility analysis methodology.” J. Struct. Eng. 128 (1): 32–38. https://doi.org/10.1061/(ASCE)0733-9445(2002)128:1(32).
Roueche, D. B., F. T. Lombardo, and D. O. Prevatt. 2017. “Empirical approach to evaluating the tornado fragility of residential structures.” J. Struct. Eng. 143 (9): 04017123. https://doi.org/10.1061/(ASCE)ST.1943-541X.0001854.
Roueche, D. B., and D. O. Prevatt. 2013. “Residential damage patterns following the 2011 Tuscaloosa, AL and Joplin, MO tornadoes.” J. Disaster Res. 8 (6): 1061–1067. https://doi.org/10.20965/jdr.2013.p1061.
Roueche, D. B., D. O. Prevatt, and F. T. Lombardo. 2018. “Epistemic uncertainties in fragility functions derived from post-disaster damage assessments.” ASCE-ASME J. Risk Uncertainty Eng. Syst. Part A: Civ. Eng. 4 (2): 04018015. https://doi.org/10.1061/AJRUA6.0000964.
Satrio, M. A., D. J. Bodine, A. E. Reinhart, T. Maruyama, and F. T. Lombardo. 2020. “Understanding how complex terrain impacts tornado dynamics using a suite of high-resolution numerical simulations.” J. Atmos. Sci. 77 (10): 3277–3300. https://doi.org/10.1175/JAS-D-19-0321.1.
Sills, D. M., G. A. Kopp, L. Elliott, A. L. Jaffe, L. Sutherland, C. S. Miller, J. M. Kunkel, E. Hong, S. A. Stevenson, and W. Wang. 2020. “The northern tornadoes project: Uncovering Canada’s true tornado climatology.” Bull. Am. Meteorol. Soc. 101 (12): E2113–E2132. https://doi.org/10.1175/BAMS-D-20-0012.1.
Smith, D. J., and D. Sutter. 2013. “Response and recovery after the Joplin tornado: Lessons applied and lessons learned.” Independent Rev. 18 (2): 165–188.
SPC (Storm Prediction Center). 2019. “Severe weather event review for Tuesday February 28, 2017.” Accessed March 11, 2020. https://www.spc.noaa.gov/exper/archive/event.php?date=20170228.
Ukkusuri, S. V., X. Zhan, A. M. Sadri, and Q. Ye. 2014. “Use of social media data to explore crisis informatics: Study of 2013 Oklahoma tornado.” Transp. Res. Rec. 2459 (1): 110–118. https://doi.org/10.3141/2459-13.
van de Lindt, J. W., S. Pei, T. Dao, A. Graettinger, D. O. Prevatt, R. Gupta, and W. Coulbourne. 2013. “Dual-objective-based tornado design philosophy.” J. Struct. Eng. 139 (2): 251–263. https://doi.org/10.1061/(ASCE)ST.1943-541X.0000622.
Wakimoto, R. M., Z. Wienhoff, H. B. Bluestein, and D. Reif. 2018. “The Dodge City tornadoes on 24 May 2016: Damage survey, photogrammetric analysis combined with mobile polarimetric radar data.” Mon. Weather Rev. 146 (11): 3735–3771. https://doi.org/10.1175/MWR-D-18-0125.1.
Womble, J. A., R. L. Wood, and M. E. Mohammadi. 2018. “Multi-scale remote sensing of tornado effects.” Front. Built Environ. 4 (Nov): 66. https://doi.org/10.3389/fbuil.2018.00066.
Womble, J. A., R. L. Wood, D. A. Smith, E. I. Louden, and M. E. Mohammadi. 2017. “Reality capture for tornado damage to structures.” In Proc., Structures Congress 2017, 134–144. Reston, VA: ASCE.
Wurman, J. 2002. “The multiple-vortex structure of a tornado.” Weather Forecasting 17 (3): 473–505. https://doi.org/10.1175/1520-0434(2002)017%3C0473:TMVSOA%3E2.0.CO;2.
Wurman J., and S. Gill. 2000. “Finescale radar observations of the Dimmitt, Texas (2 June 1995), Tornado.” Mon. Weather Rev. 128 (7): 2135–2164. https://doi.org/10.1175/1520-0493(2000)128%3C2135:FROOTD%3E2.0.CO;2.
Wurman, J., K. Kosiba, P. Robinson, and T. Marshall. 2014. “The role of multiple-vortex tornado structure in causing storm researcher fatalities.” Bull. Am. Meteorol. Soc. 95 (1): 31–45. https://doi.org/10.1175/BAMS-D-13-00221.1.
Wurman, J. A., and C. R. Alexander. 2005. “The 30 May 1998 Spencer, South Dakota, storm. Part II: Comparison of observed damage and radar-derived winds in the tornadoes.” Mon. Weather Rev. 133 (1): 97–119. https://doi.org/10.1175/MWR-2856.1.
Information & Authors
Information
Published In
Natural Hazards Review
Volume 23 • Issue 1 • February 2022
Copyright
© 2021 American Society of Civil Engineers.
History
Received: Sep 4, 2020
Accepted: Jun 21, 2021
Published online: Sep 22, 2021
Published in print: Feb 1, 2022
Discussion open until: Feb 22, 2022
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.